Arrangement in protecting relays for liquid-filled electrical apparatus



y 2, 1953 E. STENKVIST ET AL ARRANGEMENT IN PROTECTING RELAYS FORLIQUID-FILLED ELECTRICAL APPARATUS Filed Aug. 6, 1947 IN VEN TORS: EM/LSTE/VK w: r ERIK GunMu/varso/v 14 TIDE/V5) Patented May 12 1953ARRANGEMENT ,IN PROTECTING RELAYS FOR LIQUID-FILLED ELECTRICAL AP-PARATUS Emil 'Stenkvistand Erik Gudmundsson, Ludvika,

Sweden, assignors to Allmanna Svenska Elektriska Aktiebolaget, Vasteras,Sweden, a Swedish corporation Application August 6, 1947, Serial ,No."766,706 In Sweden May 5, 1945 Section 1, Public Law 690, August 8,,1946 1 Patent expires May 5, 1965 2 Claims. 1

In liquid filled electrical apparatus provided with expansion vessels,it is usual to provide a protecting relay in the pipe line between theapparatus and the expansion vessel and, on the development of gas in theapparatus, such relay gives a warning signal and in the event of largerfaults releases the apparatus, Protecting relays of this type have beencommonly employed in Europe and Canada for several years, see forexample Gross, Transformer Protection Electric Engineering of June 1947,pages 564-569. When any defect occurs in the pro tecting relay itself,the movable parts thereof must be removed for repair or inspection andthis is ordinarily a simple operation, since all movable parts areusually fastened to a cover or plate on the relay housing, so that thehousing itself may remain in the pipe line and it is only necessary toremove the said cover for repair or inspection of the parts. In order toremove the cover from the housing, however, all oil must first be drawnofi from the expansion vessel, so that the protecting relay will beentirely free from oil. In certain large transformers and otherapparatus the quantity of oil in the expansion vessel may amount toseveral tons, and the operation of drawing off and refilling the oil istherefore very costly. In such cases the protecting relay has beenheretofore provided with ordinary stop-cocks, one on each side thereof,and a shunting pipe line has also been provided with a stop-cocktherein. The shunting pipe line is necessary for the breathing of thetransformer during the time the stop-cocks of the relay are closed andsuch an arrangement of stop-cocks and shunting pipe lines occupies avery large space and is expensive to make and is, as a rule, notprovided as standard but only on special order.

The present invention has for its object to overcome these objectionsconnected with the arrangement above described, and according to thisinvention special valve means are contained within the relay-housing,such means having dimensions as small as possible and serving to shutoff the relay chamber from its inlet and outlet pipe lines, and therelay-housing is provided with a by-pass duct within the relayhousing.

The present invention is more clearly described with reference to theaccompanying drawing, which shows a longitudinal section of anarrangement according to the present invention.

In accordance with the present invention the pipe lines 2, 2 leadrespectively to a transformer casing and to its expansion vessel (notshown on the drawing). The relay-housing 9 has inserted therein twovalve discs H3, which are opened and closed by means of eccentric discsor cams ll fixed on shafts 12, which extend through the Wall of thehousing and may be conveniently turned from the outside of the housing.The valve discs H) are movable in a straight line towards or away fromthe valve seats l3, and the movement of each of the eccentric discs I lis transmitted to its valve disc it] through the medium of a bail i5,which is secured to the valve disc Ill. For this purpose each bail l5has two guide slots 16 so that the bail I5 together with the valve discH) is moved towards or away from the valve seat It, when the shaft i2 isturned. In the drawing the valves are shown in dotted lines in theirclosed position and in full lines in their open position. Thedot-anddash lines I? indicate the housing cover l'l supporting in theusual manner the mechanism of the fluid-actuated relay. By the use of aneccentric disc or cam for the operation of each valve, the arrangementrequires very little space and the dimensions of the valves need not beincreased. In the arrangement shown, the shunting by-pass I4 iscontained within the relay-housing 9 and this by-pass is not providedwith a stop-cock since the cross-sectional area of this by-pass is sosmall that the by-pass may remain permanently open without interferingwith the function of the relay.

The fluid-operated protecting relay itself may be of any well-knowntype, and may, for example, comprise a float actuated by the level ofthe liquid in the housing and a member actuated by the flow through thehousing.

We claim as our invention:

1. A device for insertion in a pipe line between a liquid-filledelectric apparatus and its expansion vessel, comprising relay meansresponsive to at least one condition of liquid at the relay means, ahousing forming a relay chamber accommodating said means, a detachablecover for said chamber, inlet and outlet ducts in the housing, two valvemeans, one on the inlet and one on the outlet side of said chamber, anda restricted duct formed within said housing and lay-passing said valvemeans, each of said valve means including a valve consisting of a valvedisc adapted to be moved away from and towards its seat, a slotted bailfixed to said valve disc, cam means located in said bail, and a shaftfixed eccentrically to said cam and extending through the slots of saidbail and through one wall of the housing.

2. A protecting device for insertion in a pipe line between aliquid-filled electric apparatus and its expansion vessel, comprisingrelay means responsive to at least one condition of liquid at the relaymeans, a housing forming a chamber accommodating said relay means, adetachable plate carried on the housing for giving access to said relaymeans, fluid ducts formed in the ends of said housing for the passage offluid through said chamber, valve seats formed around said ducts andaligned with each other, valve discs mounted for movement towards andaway from each other to engage and disengage said seats, slotted bailsfixed on said valve discs, valve operating cam means located in saidbails, actuating shafts fixed to said cam means and extending throughthe slots in said bails and through one wallof the housing, and arestricted duct formed Within one wall of the housing and permanentlyby-passing said valve seats.

EMIL STENKVIST. ERIK GUDMUNDSSON.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Name Date Powell July 5, 1859 Frenier May 24, 1921 Schaefer May30, 1922 Dean Feb. 12, 1924 Gray Nov. 15, 1927 Patterson Jan. 1, 1929Ray Feb. 3, 1931 Dowd Sept. 5, 1933 Mullen Apr. 10, 1934 Ingram June 24,1941 FOREIGN PATENTS Country Date Austria Of 1938

